1. Technical Field
Systems and devices consistent with the present invention relate to water discharge systems, and more particularly, to a water discharge system that starts water discharge upon detection of an object.
2. Description of the Related Art
A related art water discharge system has been known that automatically starts water discharge by detecting an object, for example when it is detected that the object has reached a destination.
In addition, a related art system has been known in which a detectable range of a sensor is limited, for example, to a region where only a user's hands can be detected, and starts water discharge when the user's hands reach a destination near a spout, thereby preventing erroneous detection of other objects.
In the related art water discharge system, when a transmission wave such as a microwave reaches an object to be detected, a reflected wave (also referred to as a transmitted wave) is generated. The object can be detected by the reflected wave.
For example, JP-A-9-80150 describes a related art object detecting system in which a sensor detects a reflected wave of a radiated microwave from an object, a power spectrum of a Doppler frequency signal thereof is calculated, and a peak value and a threshold value are compared with each other, thereby detecting the object.
However, there are a few disadvantages in the related art. For example, in a case where it is detected that the object, such as a body or user's hands, reaches the destination and then the water discharge is started, there is a disadvantage in that the timing of the water discharge is delayed.
The power spectrum of the Doppler frequency signal depends on a distance to the sensor and an area of the reflecting object. Accordingly, it is difficult to obtain a reflected wave having a sufficient intensity in accordance with a direction of the object placed near the spout, particularly when the object is small, such as a palm, and thus it is difficult to accurately detect the inserted hand.